checksum algorithm is not MD5 only [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56290 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/pstore.rb

@@ -395,7 +395,7 @@ class PStore
   # Load the given PStore file.
   # If +read_only+ is true, the unmarshalled Hash will be returned.
   # If +read_only+ is false, a 3-tuple will be returned: the unmarshalled
-  # Hash, an MD5 checksum of the data, and the size of the data.
+  # Hash, a checksum of the data, and the size of the data.
   def load_data(file, read_only)
     if read_only
       begin